{"id":"CVE-2026-74348","url":"https://www.cyber-defence.io/tools/cve/CVE-2026-74348","generatedAt":"2026-10-28T00:52:12.637Z","title":"In the Linux kernel, the following vulnerability has been resolved: ocfs2/dlm: require a ref for locking_state debugfs open debug_lockres_open() copies inode->i_private into struct debug_lockres and debug_lockres_release() later drops that pointer with…","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nocfs2/dlm: require a ref for locking_state debugfs open\n\ndebug_lockres_open() copies inode->i_private into struct debug_lockres and\ndebug_lockres_release() later drops that pointer with dlm_put().  That\nonly works if open successfully pins the struct dlm_ctxt.\n\nToday open calls dlm_grab(dlm) but ignores its return value.  Once the\nlast domain unregister has removed the context from dlm_domains,\ndlm_grab() returns NULL, yet open still stores the raw pointer and returns\nsuccess.  The later release path is outside the debugfs removal barrier,\nso it can call dlm_put() after dlm_free_ctxt_mem() has freed the context. \nKASAN reports this as a slab-use-after-free in dlm_put() called from\ndebug_lockres_release().\n\nFail the open when dlm_grab() cannot acquire the reference and unwind the\nseq_file private state before returning.  That keeps locking_state from\nhanding out a file descriptor whose release path does not own the\ndlm_ctxt.\n\nThe buggy scenario involves two paths, with each column showing the order\nwithin that path:\n\nlocking_state debugfs open:          last domain unregister:\n1. debug_lockres_open() reads        1. dlm_unregister_domain() calls\n   inode->i_private.                    dlm_complete_dlm_shutdown().\n2. debug_lockres_open() calls        2. shutdown removes the dlm_ctxt from\n   dlm_grab(dlm) and gets NULL.         dlm_domains.\n3. open still stores the raw dlm     3. final teardown reaches\n   pointer in dl->dl_ctxt and           dlm_free_ctxt_mem() and frees it.\n   returns success.\n4. debug_lockres_release() later\n   calls dlm_put(dl->dl_ctxt).\n\nValidation reproduced this kernel report:\nKASAN slab-use-after-free in dlm_put+0x82/0x200\nRIP: 0033:0x7f4d349bc9e0\nThe buggy address belongs to the object at ffff888103a3c000 which belongs\nto the cache kmalloc-2k of size 2048\nThe buggy address is located 816 bytes inside of freed 2048-byte region\n[ffff888103a3c000, ffff888103a3c800)\nWrite of size 4\nCall trace:\n  dump_stack_lvl+0x66/0xa0 (?:?)\n  print_report+0xd0/0x630 (?:?)\n  dlm_put+0x82/0x200 (?:?)\n  srso_alias_return_thunk+0x5/0xfbef5 (?:?)\n  __virt_addr_valid+0x188/0x2f0 (?:?)\n  kasan_report+0xe4/0x120 (?:?)\n  kasan_check_range+0x105/0x1b0 (?:?)\n  debug_lockres_release+0x53/0x80 (fs/ocfs2/dlm/dlmdebug.c:587)\n  dlm_put+0x9/0x200 (?:?)\n  debug_lockres_release+0x5c/0x80 (fs/ocfs2/dlm/dlmdebug.c:587)\n  full_proxy_release+0x67/0x90 (?:?)\n  __fput+0x1df/0x4b0 (?:?)\n  do_raw_spin_lock+0x10f/0x1b0 (?:?)\n  fput_close_sync+0xd2/0x170 (?:?)\n  __x64_sys_close+0x55/0x90 (?:?)\n  do_syscall_64+0x10c/0x640 (arch/x86/entry/syscall_64.c:87)\n  irqentry_exit+0xac/0x6e0 (?:?)\n  entry_SYSCALL_64_after_hwframe+0x77/0x7f (?:?)\nFreed by task stack:\n  kasan_save_stack+0x33/0x60 (?:?)\n  kasan_save_track+0x14/0x30 (?:?)\n  kasan_save_free_info+0x3b/0x60 (?:?)\n  __kasan_slab_free+0x5f/0x80 (?:?)\n  kfree+0x30f/0x580 (?:?)\n  dlm_put+0x1ce/0x200 (?:?)\n  dlm_unregister_domain+0xf6/0xb30 (?:?)\n  o2cb_cluster_disconnect+0x6b/0x90 (?:?)\n  ocfs2_cluster_disconnect+0x41/0x70 (?:?)\n  ocfs2_dlm_shutdown+0x1c4/0x220 (?:?)\n  ocfs2_dismount_volume+0x38a/0x550 (?:?)\n  generic_shutdown_super+0xc3/0x220 (?:?)\n  kill_block_super+0x29/0x60 (?:?)\n  deactivate_locked_super+0x66/0xe0 (?:?)\n  cleanup_mnt+0x13d/0x210 (?:?)\n  task_work_run+0xfa/0x170 (?:?)\n  exit_to_user_mode_loop+0xd6/0x430 (?:?)\n  do_syscall_64+0x3cb/0x640 (arch/x86/entry/syscall_64.c:87)\n  entry_SYSCALL_64_after_hwframe+0x77/0x7f (?:?)","published":"2026-08-15T06:22:36.000Z","lastModified":"2026-08-17T06:19:29.000Z","status":"Received","sourceIdentifier":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","cvss":null,"cwe":[],"affected":[],"epss":{"score":0.0022,"percentile":0.12371,"date":"2026-10-26","history":[]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"unknown","text":"Not yet scored. NVD analysis is pending; check back once CVSS and EPSS values are published."},"changes":[],"references":[{"url":"https://git.kernel.org/stable/c/03ad858ce8064861ea580021976dc19b7aabb549","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/5bee5d5f67aedd26d2b72e00e49dd93331fbcc30","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/6cc93dea4078cbcddee63fa2234e382a76600464","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/90a6512425414098a63fc97b77bed089c75d106b","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/9c81c1a61a52b6ecf0d14f1dbd95f154a7a9e92a","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/a087b2d3411e7f9df71ba3293596923ee2c70d65","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/a09831214912a1f270663d935613910fafd8d883","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/aa7883b6a3c76301a3299deb34de948e73bb6a08","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-74348","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}